This invention generally relates to a method of treating polymeric materials, such as ophthalmic lenses and medical devices. In particular, this invention is directed to a coating/printing method and apparatus for modifying the surface properties and/or functions of an ophthalmic lens or a medical device.
Many devices used in biomedical applications require that the bulk of the device have one property, while the surface of the device has another property. For example, contact lenses may have high oxygen permeability through the lens to maintain good corneal health. However, materials that exhibit exceptionally high oxygen permeability (e.g. polysiloxanes) are typically hydrophobic and will adhere to the eye. Thus, a contact lens generally has a core or bulk material that is highly oxygen permeable and hydrophobic, and a surface that has been treated or coated to increase hydrophilic properties, thereby allowing the lens to freely move on the eye without adhering excessive amounts of tear lipid and protein.
In order to modify the hydrophilic nature of a relatively hydrophobic contact lens material, a contact lens can be treated with a plasma treatment. For example, a high quality plasma treatment technique is disclosed in PCT Publication No. WO 96/31793 to Nicholson et al. Some plasma treatment processes, however, require a significant monetary investment in certain equipment. Moreover, plasma treatment requires that the lens be dry before exposure to the plasma. Thus, lenses that are wet from prior hydration or extraction processes must be dried, thereby imposing added costs of obtaining drying equipment, as well as added time in the overall lens production process. As a result, a number of methods of altering the surface properties of polymeric biomaterials, such as contact lenses, have been developed. Some of these techniques include Langmuir-Blodgett deposition, controlled spin casting, chemisorption, and vapor deposition. Useful examples of Langmuir-Blodgett layer systems are disclosed in U.S. Pat. Nos. 4,941,997; 4,973,429; and 5,068,318.
A more recent technique used for coating electronic devices is a layer-by-layer (xe2x80x9cLbLxe2x80x9d) polymer absorption process, which is described in xe2x80x9cInvestigation of New Self-Assembled Multilayer Thin Films Based on Alternately Adsorbed Layers of Polyelectrolytes and Functional Dye Moleculesxe2x80x9d by Dongsik Yoo, et al. (1996). The process described in this article involves alternatively dipping hydrophilic glass substrates in a polyelectrolyte solution (e.g., polycations such as polyallylamine or polyethyleneimine) and then in an oppositely charged dye solution to form electrically conducting thin films and light-emitting diodides (LEDs). After each dipping, the substrates are rinsed with acidic aqueous solutions. Both the dipping and rinsing solutions have a pH of 2.5 to 7. Prior to dipping, the surfaces of the glass substrates are treated in order to create a surface having an affinity for the polyelectrolyte.
Similar to the above process, two other processes are described by 1995 publications entitled xe2x80x9cMolecular-Level Processing of Conjugated Polymersxe2x80x9d by Fou and Rubner and Ferreira and Rubner, respectively. These processes involve treating glass substrates that have hydrophilic, hydrophobic, negatively, or positively charged surfaces. The glass surfaces are treated for extended periods in hot acid baths and peroxide/ammonia baths to produce a hydrophilic surface. Hydrophobic surfaces are produced by gas-phase treatment in the presence of 1,1,1,3,3,3-hexamethyldisilazane for 36 hours. Charged surfaces are prepared by covalently anchoring charges onto the surface of the hydrophilic slides. For example, positively charged surfaces are made by further treating the hydrophilic surfaces in methanol, methanol/toluene, and pure toluene rinses, followed by immersion in (N-2 aminoethyl-3-aminopropyl) trimethyloxysilane solution for 12 to 15 hours. This procedure produces glass slides with amine functionalities, which are positively charged at a low pH.
In addition to the above-described techniques, U.S. Pat. Nos. 5,518,767 and 5,536,573 to Rubner et al. describe methods of producing bilayers of p-type doped electrically conductive polycationic polymers and polyanions or water-soluble, non-ionic polymers on glass substrates. These patents describe extensive chemical pre-treatments of glass substrates that are similar to those described in the aforementioned articles.
The methods described above generally relate to layer-by-layer polyelectrolyte deposition. However, these methods require a complex and time-consuming pretreatment of the substrate to produce a surface having a highly charged, hydrophilic, or hydrophobic nature in order to bind the polycationic or polyanionic material to the glass substrate.
To reduce the complexity, costs, and time expended in the above-described processes, a layer-by-layer polyelectrolyte deposition technique was developed that could be effectively utilized to alter the surfaces of various materials, such as contact lenses. This technique is described in co-pending U.S. patent application Ser. No. 09/199,609 filed on Nov. 25, 1998. In particular, a layer-by-layer technique is described that involves consecutively dipping a substrate into oppositely charged polyionic materials until a coating of a desired thickness is formed. Nevertheless, although this technique provides an effective polyelectrolyte deposition technique for biomaterials, such as contact lenses, a need for further improvement still remains.
For example, this current LbL deposition technique is not capable of applying two or more materials having different properties/functionalities onto biomaterials, such as contact lenses, to form property/functionality patterns on the surfaces of the biomaterials. Such patterns can comprise multiple sets of zones each of which may have an unique property or functionality. Contact lenses with a plurality of different property/functionality zones may be useful, for example, for enhancing wearer""s comfort and health and for administrating medicines to patients in a timely-controllable manner.
Another example is that this current LbL deposition technique is not capable of applying asymmetrically one coating material to one of the two surfaces of an intraocular lens and another different coating material to the other surface of that intraocular lens. Such asymmetrically coated intraocular lenses can have different surface properties, for example, one surface being hydrophobic and the other surface being hydrophilic.
As such, a need currently exists for a versatile method of applying different materials to form a coating on an ophthalmic lens or medical device. In particular, a need exists for a method of forming an coating with zones of different surface properties and/or functions onto contact lenses or medical devices.
An objective of the invention is to provide methods and systems for applying a layer of liquid coating to an ophthalmic lens or a mold used to produce the ophthalmic lens or a medical device other than ophthalmic lens.
Another objective of the invention is to provide an ophthalmic lens the surface of which is modified to increase wettability and thereby to increase further the wearer""s comfort by using the above methods and systems of the invention.
A further objective of the invention is to provide a method for making an ophthalmic lens or a medical device other than ophthalmic lens, wherein the ophthalmic lens or medical device has a surface having two or more sets of zones each having a different surface property and/or function.
Still a further objective of the invention is to provide an ophthalmic lens or a medical device other than ophthalmic lens having a color image or a color image with a property/functionality pattern or micro-pattern.
The foregoing and other objectives are achieved by the various aspects of the invention described herein.
The invention, in one aspect, provides a method of applying a coating to an object, the method comprising spraying at least one layer of a coating liquid onto the object using a spraying process selected from the group consisting of an air-assisted atomization and dispensing process, an ultrasonic-assisted atomization and dispensing process, a piezoelectric assisted atomization and dispensing process, an electro-mechanical jet printing process, a piezo-electric jet printing process, a piezo-electric with hydrostatic pressure jet printing process, and a thermal jet printing process.
The invention, in another aspect, provides a method of applying a coating to an object, the method comprising: (a) spraying a first layer of a first coating liquid onto the object using a spraying process selected from the group consisting of an air-assisted atomization and dispensing process, an ultrasonic-assisted atomization and dispensing process, a piezoelectric assisted atomization and dispensing process, an electro-mechanical jet printing process, a piezo-electric jet printing process, a piezo-electric with hydrostatic pressure jet printing process, and a thermal jet printing process and (b) spraying at least a second layer of a second coating liquid onto the object using a spraying process selected from the group consisting of an air-assisted atomization and dispensing process, an ultrasonic-assisted atomization and dispensing process, a piezoelectric assisted atomization and dispensing process, a piezo-electric jet printing process, a piezo-electric with hydrostatic pressure jet printing process, and a thermal jet printing process.
The invention, in still another aspect, provides a method for producing a property/functionality pattern on a surface of an object, the method comprising the steps of applying a plurality of layers of one or more coating materials with different surface properties and/or functions, using a spraying process selected from the group consisting of an air-assisted atomization and dispensing process, an ultrasonic-assisted atomization and dispensing process, a piezoelectric assisted atomization and dispensing process, an electro-mechanical jet printing process, a piezo-electric jet printing process, a piezo-electric with hydrostatic pressure jet printing process, and a thermal jet printing process, and obtaining a coating having the property/functionality pattern on the object.
The invention, in yet another aspect, provides a method for making a contact lens having a color image thereon.
The invention, in a further aspect, provides an apparatus for applying a coating to an ophthalmic lens comprises: a means for securing the ophthalmic lens and a spraying device capable of spraying a layer of a coating liquid onto the ophthalmic lens using a spraying process selected from the group consisting of an air-assisted atomization and dispensing process, an ultrasonic-assisted atomization and dispensing process, a piezoelectric assisted atomization and dispensing process, an electro-mechanical jet printing process, an electro-mechanical jet printing process, a piezo-electric jet printing process, a piezo-electric with hydrostatic pressure jet printing process, and a thermal jet printing process.
The invention, in still a further aspect, provides an automated apparatus for applying a coating to an ophthalmic lens in a precision manner comprises: a means for securing the ophthalmic lens; a spraying device capable of spraying a layer of a coating liquid onto the ophthalmic lens using a spraying process selected from the group consisting of an air-assisted atomization and dispensing process, an ultrasonic-assisted atomization and dispensing process, a piezoelectric assisted atomization and dispensing process, an electro-mechanical jet printing process, an electro-mechanical jet printing process, a piezo-electric jet printing process, a piezo-electric with hydrostatic pressure jet printing process, and a thermal jet printing process; and a computer system capable of controlling the positioning of the dispensing head of the spraying device on the ophthalmic lens and dispensing the coating liquid.
These and other aspects of the invention will become apparent from the following description of the presently preferred embodiments taken in conjunction with the following drawings. The detailed description and drawings are merely illustrative of the invention and do not limit the scope of the invention, which is defined by the appended claims and equivalents thereof. As would be obvious to one skilled in the art, many variations and modifications of the invention may be effected without departing from the spirit and scope of the novel concepts of the disclosure.